Is it ok to use null checks?

[wolle]

I feel like checking for null is bad design but if so, why Java allows it in first place? Please let me know your thoughts.

The inventor of the null reference, Tony Hoare, has publicly apologized for it. He calls it his billion-dollar mistake. See this Wikipedia entry (the first paragraph in the Apologies and retractions section)

https://en.wikipedia.org/wiki/Tony_Hoare

It beats me why Java introduced it, and even more so, why they haven't done anything about it? Even the NullPointerException-message itself is a misnomer because there are no pointers in Java.

I don't see how you can avoid every possibility of a NullPointerException sneaking in, not even with the most careful of designs. Not as long as there are people who do the programming. Experienced programmers tend to be defensive. I think they will keep adding safeguards to avoid embarrassing runtime errors in their code. Defensive checking is even considered a good Java idiom by many. Mistakes happen, also in well-designed programs.